Noise eliminator for fluid systems



W. A. HUNTER ETAL NOISE ELIMINATOR FOR FLUID SYSTEMS Julyl 27, 1954 Filed Aug. 17, 1950 MN. @A

Patented July 27, 1954 NOISE ELIMINATOR FOR FLUID SYSTEMS William A. Hunter, Highland Park, and Walter P. Cousine, Detroit, Mich., assignors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application August 17, 1950, Serial No. 180,026

The present application relates to a noise eliminator for a iiuid pressure system particularly fluid pressure systems including positive displacement pumps.

It may be readily demonstrated that while a gear type pump may befound to be quiet in operation under moderate heads, the same pump will become excessively noisy when operating under high pressures say of the order of.600 to 800 pounds per square inch. One explanation advanced is that the rubber or other hose on the discharge side of the pump tends to rigidify under the high pressure and transfer pump pulses away from the pump in an undiminished state much the same as metal pipe would do. By Way of eliminating this difficulty, rather satisfactory results may perhaps be obtained by the interposition of an air dome in the output hose or simply by use of a great length of hose in effort to damp out the pump pulsations; yet theseV approaches are generally open to the criticism of wasted space and unsightliness particularly in compact pump: installations. According to a feature of the present invention, a conduit is provided between a high pressure pump and a device receiving output from the pump of which the appearance is trim yet the eifectiven'ess is satisfactory.

According to another feature, a noise eliminator is provided for high pressure pump work which is easy to fabricate and formed of relatively inexpensive and uncomplicated parts. Moreover, little or no maintenance on the noise eliminator is required in service.

According to still another feature of the invention, a noise-eliminating conduit is provided for the outlet side of a high pressure pump which requires but small space and vordinarily only substantially the same length of hose as required to bridge the gap between the pump and the device adapted to receive the pump output.

Further features, objects, and advantages will either be specifically pointed out or become apparent when, for a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawings in which:

Figure 1 shows the invention applied to an hydraulic steering system;

Y Figure 2 is a section through the fitting forming a hose restriction; and Y Figure 3 shows a modiedvform of hose and restriction.

In particular regard to Figure l, the steering gear generally indicated at I is effective bei 5 Claims. (Cl. 13S-2G) CTI tween the steering wheel I2 of a vehicle and a steerable road wheel;I I4 for providing power operation of the latter. Road wheel I4 is provided with a suitable tire I6 and is steered by structure including a knuckle arm I8 suitably connected to a tie rod 20. Tie rod 20 is carried at its rear end by means of a pivot 22. Steering wheel I2 is mounted to a steering column 24 having a worm portion 26. Worm 26 meshes with a toothed sector 28 suitably Supported to rotate on a rock shaft 30. Fixed to rock shaft 30 for coordinated Vrotation with sector 28 is an arm 34 which carries a pivot 35. Moving with pivot 36 is a chain of links 38 and 48 mutually interconnected by a pin 42. Carried at one end of link 48 and rigid therewith, is a valve 44. An intake port or opening 4S in steering gear I0 is provided adjacent valve 44 and registers with an opening 48 provided in a sleeve 50 within which valve 44 is received for rectilinear movement. Valve 44 has valve parts 52 and 54 mutually spaced from one another and commonly traversed between their outer ends by an equalizing passage 56. Controlled by valve parts 52 and 54 respectively, are valve openingsv 51 and 58 formed in sleeve 50. By appropriate and coordinated control over valve openings 51 and 58, fluid may be bypassed around or delivered into or discharged from the chambers 62 and 64 of a cylinder in which is received a slidable piston 60. A return line 6B is provided for chamber 6'2 and a similar return line 86 is provided for chamber 64, both said lines effecting connection with a reservoir 68. Piston is carried by a piston rod I8 having a rack 'I2 thereon provided with a portion slidably received in a iluidtight seal 13. A toothed sector 'I4 meshes with rack '.'2 for appropriate rotation upon a rock shaft I8 mounted in the case of steering gear I8. Fixed to shaft I5 for coordinated movementwith sector I4 is an arm 18 which carries the pin 22 connected to tie rod 20 for the steering gear.

By means of a pin and slot connection 8G the piston rod 'I0 is linked for movement with a link 82 having at its upper end a pin and slot connection at 84 with the valve sleeve 58. Reservoir 68, into which the return linesV S5 and 3G deliver pressure fluid, is provided with a Suction line 88 providing a connection with the inlet port 90 of a positive displacement pump 92 n which may be of the gear type. Outer and inner rotors 9| and 93 are mounted in pump 92 for eccentric rotation relative to one another, the Y inner rotor 93 having one less than the number of teeth or lobes of the outer rotor 9|. The differential in teeth accounts for the fact that together the eccentric rotors define mutually separated chambers 95 therebetween which in eiiect rotate between inlet port 9E! and the discharge port Q4 for pump 92. Due to the rotation, fluid is trapped and transferred into the discharge port Si against the residual pressure therein. The outlet line for discharge Q4 is provided with a flow-sensitive device 9G which bypasses through a line 98", excessive fluid into suction line 83. There may be provided in the discharge line for pump 92 a T Imi connecting with a relief line Iil2 provided with a pressure relief valve imi suitably returning fluid into the reservoir 68. A nipple Iilis received in T Iil to connect thereto a fitting m8 mounted to sleeve H2 firmly secured to the end of a rubber hose IID. Rubber hose ila is especially adapted to be transversely elastic and the walls H4 thereof are suitably fabricated and proportioned to produce such an effect.

Cooperating with rubber hose IIG to provide a conduit between steering gear Ia and pump 92 is a hose I l@ of manifestly smaller diameter than hose II. Hose H6 is flexible longitudinally such as to take up the foreshortened eifect of hose Il@ as the latter expands transversely of itself. At one end hose I I carries a sleeve I I8, mounted to which is an end fitting 12a suitably connected by a nipple I22 to steering gear Ill. The large and small hoses IIB and IIS are connected together at their inner ends by sleeves i211 and 126.

With particular respect to Figure 2, the sleeves i211 and I25 between the hose sections may 'be seen f to be located relatively adjacent to one another. Sleeve i215 is provided with internal threads i125 for reception of the end of hose Ii. An inner fitting is provided with a threaded portion ISE threaded at it@ with threads preferably of the opposite hand to threads |29. Fitting portion 132 is screwed internally into the hose Ilia. Appropriately connected tc portion i532 by welding or soldering, is a portion i3d of the inner fitting. Portion |34? is provided with threads |35 preferably of the opposite hand, to the internal threads 33 formed on sleeve Ii. Threadably received between the sleeve IZ and the inner litting portion i3d is the end of the small hose lit.

The operation of the device of Figures l and. 2 briefly is as follows. In response to appropriate movement of the steering wheel I2, valve il may be appropriately shifted to uncover relatively more of either valve openings El or 5S as respects inlet port de supplied by pump e2. inasmuch as the steering gear I6 is of the open valve type, less fluid will tend to be bypassed around the valve opening which has been opened farther and duid will tend to be diverted into either chamber E2 or Eid for operating piston Ei. At the same time the opposite chamber for piston 5t will be opened more to discharge, either through return line S6 or 8% and the force differential due to unequal pressures existing across piston lid will cause the piston G to move to operate knuckle arm i8 and the road wheel i4. Coordinated for movement with the steering of road wheel Is is the valve sleeve 5d operated by interconnecting link 82. As the road wheel I responds to the movement of steering wheel I2, sleeve 5l! will tend to be shifted and the steering system returned to a neutralized or re-centered position. Under the circumstances, when piston Bil is being moved under hydraulic pressure, it may be readily seen that the fluid is being introduced into the discharge port irs 94 of the pump by divided quantities which are separately handled in the individual chambers 94 dened by the eccentrically-mounted rotors 9! and 93. Under excessive pressures of say, the order of 600 to 800 pounds per square inch, the addition of these quantities of fluid into an ordinary pump conduit will tend to cause pulses to be transmitted directly into steering gear Il) and to be reflected by an objectionable vibratory noise. As may be noted particularly in Figure 2, however, owing to the fact that a restriction M2 is formed by the inner fitting and the fact that hose I It is of markedly smaller diameter than hose I IB, there is established a coaction tending to prevent the pulsations from being transmitted to or through the smaller hose I IE. As previously pointed out, rubber hose I I0 is transversely elastic and can expand and contract in order to dissipate the pulsations as they approach restriction |42. The flexible hose I I6 has portions extending in a direction generally transverse of the axis of the hose section IIB and provides for adequate end movement of the transversely expanding and contracting hose portion I le by bodily deflection of the more limber hose section Il@ and causes the system to lend itself to a smooth and quiet behavior.

With respect to Figure 3, a hose 369 of uniform cross section may be provided for connection between the T S and a steering gear ZIE] suitably supplied with pump discharge from T 30B. By means of a restriction 342 formed in an internally received fitting 332, the hose 30S may be roughly divided into two substantially equal length portions 3 I0 and 3 I A band 334 may be provided to secure the ntting 332 against longitudinal movement respecting the hose. Hose Silliis transversely elastic and is provided with walls 3 I 4 fabricated and proportioned to provide appropriate elastic qualities. Portions of these hose sections 3 I 9 and Sli extend in directions transverse with respect to each other.

It is highly desirable in the flexible conduits just set forth that the restriction fall at a location substantially equally distant from the extreme ends of the rubber hose conduit. Thus an appropriate section of hose is provided between the restriction and the pump for suitable expanding and absorbing the pulses, and another suitable section of hose is provided between the restriction and the device consuming the pressure fluid, in order to compensate for suitable end movement of the entire rubber hose conduit. Within its broader aspects, however, the invention is not necessarily limited in respect of the interposition of the restriction at a point exactly located half way between the ends of the rubber hose. By the term rubber as used in the specification and claims, is to be understood any rubber-like material of the group comprising latex, neoprene, plastics, synthetics, resins and the like-walled non-metallic materials.

Variations within the spirit and scope of the invention described are equally comprehended by the foregoing description.

What is claimed is:

l. For use in a pressure fluid system including a first liquid-supplied hydraulic device and a positive displacement hydraulic pumping device for supplying said lst hydraulic device with a stream of moving liquid, said hydraulic devices having ports adapted to be placed in communication with one another so as to accommodate passage of said stream of moving liquid: a noise-eliminatortype conduit between said ports and comprising a serially-arranged multi-section hose means including at least rst andsecond sections connected in that order effective to conduct a` stream of such moving liquid aforesaid in a manner by which pulses in said'moving stream of liquid moving therewith due to pumping are eliminated, said first section comprising a transversely expansible rubber hose section having a predetermined inside diameter, said second section comprising a relatively smaller limber hose section having an inside diameter smaller than the predetermined inside diameter of said first section, there being at least a portion of said second section which is bowed and which, by transversely deecting, operatively accommodates foreshortening of said first section due to transverse expansion of the latter in the course of the pumping operation.

2. For use in a circulatory system for power fluid comprising a pulsation-producing positivedisplacement pumping device and a power-motor control-valve-device, said pumping device having associated with it a discharged fluid outlet through which pressure fluid can be supplied from the pumping device, said control valve device having associated with it an inlet to which the pumping device can supply pressure uid for valve controlled application to the power motor: a multi-sectioned hose means adapted to be connected between theoutlet from the pumping device and the inlet of the control valve device and forming a path through which the pump-supplied pulsating fluid can be circulated, said hose means comprising a iirst and a last section connected so as to be serially arranged and dissipate energy from fluid pulsations, said first section comprising a transversely expansible rubber hose section having a predetermined inside diameter, said last section comprising a relatively smaller limber hose section having an inside diameter smaller than the predetermined inside diameter of said first section, there being at least a portion of said last section which is operatively arranged in a bow and which, by transversely deilecting, accommodates foreshortening of said first section due to vibratory transverse expansion of the latter in the course of the pulsating pumping operation.

3. For use in a circulatory system for power liquid comprising a pulsation-producing positivedisplacement pumping device, a power-motor control-valve device, a threaded fitting connected to and communicating with a discharged fluid outlet from said pumping device through which pulsating pressure liquid is supplied by the latter, and a threaded fitting connected to and communicating with an inlet to said power-motor control-valve device to which the pumping device can supply pressure liquid for the valve-controlled application thereof to the power motor, said threaded fittings being spaced apart from one another With a predetermined distance therebetween: a multi-section hose assembly of an overall length in excess of said predetermined distance between threaded fittings for forming a noiseeliminator path through which the pump-supplied pulsating liquid can be circulated, said hose assembly comprising in combination, a first and a last section connected so as to be 'serially arranged and cooperate in dissipating energy from pumped pulsating liquid, a hose fitting carried by the first section atY its outer end for threadably connecting the same to said pump-outletconnected fitting, and a hose fitting carried by the last section at its outer end for threadably connecting the same to said valve--inlet-connected fitting, said first section-being constituted by a transversely expansible rubber hose section having a predetermined inside diameter, said last section being constituted by a relatively smaller hose section having an inside diameter smaller than the predetermined inside diameter of said first section, and being of a limber construction and bowed so as to have a bodily offset portion for transversely deflecting to accommodate foreshortening of said first section due to vibratory transverse expansion of the latter in the course of the pulsating pumping operation.

4. For use in a pressure fluid system including a first hydraulically operated device and a second hydraulic pumping device for supplying said rst hydraulically operated device with a stream of pressurized moving liquid, said hydraulic devices having ports adapted to be placed in communication with one another so as to accommodate passage therebetween of said stream of moving liquid; a noise-eliminator-type conduit connectible between said ports and comprising a multisection hose means including at least first and second series arranged sections, said first section receiving the discharge from said pumping device and passing it to said second hose section and comprising a transversely expansible rubber-like hose section having a predetermined inside diameter, said second section comprising a readily flexible hose section having an inside diameter smaller than the predetermined inside diameter of said first section and being arranged with a bowed portion intermediate its ends when installed between said hydraulic devices, said bowed portion providing a hose portion adapted to be readily reshaped to operatively accommodate foreshortening of said first hose section due to transverse expansion of the latter under pulsations occurring during the transfer of pressurized liquid between said devices,

5. For use in a pressure fluid system including a rst hydraulically operated device and a second hydraulic pumping device for supplying said rst hydraulically operated device with a stream of pressurized moving liquid, said hydraulic devices having ports adapted to be placed in communication with one another so as to accommodate passage therebetween of said stream of moving liquid; a noise-eliminator-type conduit connectible between said ports and comprising a multisection hose means including at least first and second series arranged sections, said iirst section receiving the discharge from said pumping device and passing it to said second hose section and comprising a transversely expansible rubber-like hose section having a predetermined inside diameter, said second section comprising a readily flexible hose section having an insiderdianieter smaller than the predetermined inside diameter of said first section and being arranged with a portion intermediate its ends that extends at an angle to said first section when said conduit is installed between said hydraulic devices, said intermediate portion oi said second section providing a hose portion adapted to be readily rearranged to operatively accommodate foreshortening of said iirst hose section due to transverse expansion of the latter under pulsations occurring during the transfer of pressurized liquid between said hydraulic devices.

(References on following page) References Cited in the le of this patent Number UNITED STATES PATENTS fg Number Name Date 2603065 748,301 Nicholls Dec. 29, 1903 y 752,175 Monnier Feb. 16, 1904 807,595 Brewer DEC. 19, 1905 Number 2,163,892 Sanford et al June 27, 1939 231,112 2,170,890 Allen Aug. 29, 1939 253,307 2,261,028 Hopkins oct. 28, 1941 lo 711,203 2,261,948 :Beach Nov. 11, 1941 878,805 2,402,449 Rockwell June 18, 1946 Name Date Parsons Mar. 18, 1947 Bannister July 26, 1949 Sarto July 15, 1952 FOREIGN PATENTS Country Date Great Britain Mar. 26, 1925 Great Britain June 17, 1926 France Sept. 5, 1931 France Feb. 4, 1943 

